1. Field of the Invention
This invention relates to a near infrared absorbing composition (hereinafter referred to as a near IR-absorbing composition) comprising both thioamide compound and at least one compound selected from a member consisting of copper compound and lead compound, a near infrared absorbing material (hereinafter referred to as a near IR-absorbing material) comprising both compounds, and a product containing said composition or said material.
2. Prior Art
Recently, near IR-absorbing materials have been researched and developed. They have found a wide use, including light-sensitive materials using a semiconductor laser ray having a near IR-wave length range, etc. as a light source; information-recording materials such as an optical recording disk; optical materials such as IR-cut filter, IR-cut film; light-heat-converting record material used together with a heat-sensitive material.
As hitherto developed near IR-absorbing materials, there are disclosed a chrome-cobalt complex in Japanese Patent Publication No. 60-42269, a thiolnickel complex in Japanese Laid-Open Patent Application No. 60-21294, an anthraquinone derivative in Japanese Laid-Open Patent Application No. 61-115958, a novel squarylium compound having a maximum absorption in a wave length range of 700-800 nm in Japanese Laid-Open Patent Application No. 61-218551.
Further, there are described a nitroso compound, metal complex thereof, a polymethine dye (cyanine dye), a cobalt-, platinum-, or palladium-complex of thiol, Phthalocyanine dye, triarylmethane dye, immonium dye, diimmonium dye, a naphthoquinone dye, and the like in "Near IR-absorbing dyestuff" (Kagakukogyo, 43, May 1986).
Among the conventional near IR-absorbing materials, the organic materials have the defects that the durability is inferior and the original abilities deteriorate with the change of condition or the lapse of time. On the contrary, the complex-base materials, which exhibit a good durability, have defects that they are strongly colored owing to the absorption of both visible range and near infrared range, so that their uses are limited. Both materials indicate an absorption peak at a particular wave length and have little absorbency in the range of outside the particular wave length. For a recording material in which one of both materials is used and a laser ray of near IR-wave length, for example, is applied as a light source, it is required that the wave length of laser agrees with an absorption peak of one material. Since both the wave length of laser and the absorption wave length of the near IR-absorbing material are limited, the combination in which the wave length of laser agrees with the absorption peak of the near IR-absorbing material is extremely restricted. It is said that this combination hardly exists taking the absorbency, durability, coloring, costs, etc. into consideration. This use is extremely limited.